Borrowing it
Nothing to install: this file belongs to rianvdm/lastfm-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/rianvdm/lastfm-mcp/main/CLAUDE.mdgit clone --depth 1 https://github.com/rianvdm/lastfm-mcpWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/rianvdm/lastfm-mcp/claude-md)<a href="https://agentmods.dev/instructions/rianvdm/lastfm-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/rianvdm/lastfm-mcp/claude-md.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01582 | $0.01582 |
| Opus 5 | $0.00791 | $0.00791 |
| Sonnet 5 | $0.00316 | $0.00316 |
| Haiku 4.5 | $0.00158 | $0.00158 |
Grade A, and why
lastfm-mcp CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 151 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
Cloudflare Worker implementing a Model Context Protocol (MCP) server that connects AI assistants to Last.fm listening data. Runs on workerd with KV-backed persistence for sessions, caching, rate limits, and logs.
Build / Test / Lint Commands
npm run dev # Local dev server (wrangler dev, port 8787)
npm run build # Dry-run deploy to validate build (wrangler deploy --dry-run)
npm run deploy # Deploy to staging
npm run deploy:prod # Deploy to production
npm run lint # ESLint (src/**/*.ts)
npm run format # Prettier --write
npm run format:check # Prettier --check (CI)
npm run cf-typegen # Regenerate Worker type bindings (run after changing wrangler.toml; produces worker-configuration.d.ts — generated, do not edit by hand)
Running Tests
Test runner: vitest 4 with @cloudflare/vitest-pool-workers ≥0.15 (runs in workerd/miniflare). Requires Node 22 (see .nvmrc); the config uses the cloudflareTest() plugin shape, not the removed defineWorkersConfig.
npm test # All tests
npx vitest run # All tests, exit when done
npx vitest run test/utils/retry.test.ts # Single file
npx vitest run -t "should succeed" # Single test by name (matches against full describe → it path)
npx vitest run test/protocol/ # All tests in a directory
Code Style
Formatting (Prettier)
- Tabs for indentation (not spaces)
- No semicolons
- Single quotes
- 140-char print width
- LF line endings
Linting (ESLint)
@typescript-eslint/no-unused-vars: error — prefix unused params/vars with_@typescript-eslint/no-explicit-any: warn — avoid but not blocked- TypeScript strict mode is enabled
File Headers
Every file (source and test) must have exactly two // ABOUTME: comment lines at the top. Line 1 describes WHAT the file is. Line 2 describes its PURPOSE or SCOPE.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 151 lines · 1,582 tokens per session scan A 19c920753c75
lastfm-mcp CLAUDE.md is an instructions file published in the GitHub repository rianvdm/lastfm-mcp (46 stars, last pushed 10d ago), licensed MIT. It adds 1,582 tokens to every session, about $0.0079 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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